Universal screw driver



Nov. 20, 1945. V J. H. BISHOP 2,339,129

I v UNIVERSAL SCREW-DRIVER Filed Sept. s, 1945 4 OENEY:

Patented Nov. 20, 1945 2,389,129 UNIVERSAL SCREW DRIVER Joseph H.Bishop, Dayton, Ohio Application September 3, 1943, Serial No; 501,090

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757)- 1 Claim.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to screw driving tools and more particularly tothat type of such tools characterized by the provision of ascrew-engaging bit comprising a plurality of radially extending ribs,usually three or four in number, formed by the provision of eitherfluted or sharply angled recesses intermediate said ribs, which tool areadapted for screw-driving cooperation with screws provided with bitreceiving recesses corresponding in shape to the particular form of bitof the type different configuration that neither is satisfactorilyadapted for cooperation with the screwdriving tool specially designedfor the other form of screw.

In practice, therefore, it is essential that, in any operation whereboth of the aforesaid two generally standardized forms .of'said screwsare used, there be provided complete sets of screwdrivers of each typeto fit the various sizes of each of the two standardized forms ofrecessed head screws, since the screwdriving tools designed especiallyfor cooperation with one of said forms of screw are not interchangeablefor use with the other form of screw.

The principal object of this invention, therefore, has been to provide ascrewdriver bit which is adapted for use interchangeably with both ofthe aforesaid standardized forms of recessed head screws.

The various features of the invention will more clearly appear uponreference to the accompanying drawing, in which Figure 1 is an enlargedside elevation of the bit or working end of a screwdriver adapted forcooperation with one of the aforementioned standard forms of screwillustrated in Figures 2 and 3;

Figure 2 is a longitudinal sectional view of one,

of the standardized forms of screws generall in use, a portion thereofbeing broken away, the section being taken on line 2-2 of Figure 3;

' Figure 3 is a top plan view of the screw of Figure 2; I

Figure 4 is a side elevational view of the bit or working end of ascrewdriving tool designed for use particularly with the form ofrecessed head screw illustrated in Figures 5 and 6 i Figure 5 is alongitudinal sectional view through a screw of another standardized formof screw generally in use, the section being taken on line 5-5 of Figure6, a portion of the screw being broken away;

Figure 6 is a top plan view of the form of screw shown in Figure 5;

Figure 7 is a side elevational view of the bit or working end of ascrewdriver embodying my invention.

Figure 8 is an end elevation of the bit or working end of thescrewdriver of Figure 7.

The standard form of screwdriver shown in Figure 1 includes acylindrical shank portion I and a working end or screw-engaging bitgenerally indicated by the numeral 2. The bit, in this form of a,standard screwdriver, comprises four ribs 3, formed by cutting recessesin the end of the shank I intermediate the ribs 3. These recesses arecut so that the respective ribs 3 are V provided with substantially fiatsides 4. The adjacent flat sides 4 of each pair of adjacent ribs 3 meetin a sharply defined line of juncture 5 at an angle of substantiallyninety degrees, the lines of juncture 5 lying substantially midwaybetween' the adjacent sides 4 of each pair of adjacent ribs 3. Th ribs 3are conically tapered as indicated at 6 to a sharp point 1 at theextreme outer end of the bit 2.

The screw form illustrated in Figures 2 and 3 is provided with a recessgenerally indicated by the numeral 8 which is adapted to receive the bitor working end 2 of the screwdriver illustrated in Figure 1. Thecruciform recess 8 corresponds substantially to the configuration of thebit end 2. In this connection it will be understood that the walls ofthe recess 8 converge inwardly to substantially a sharp point 9 at thebase of the recess 8, the walls l0 of the recess 8 having a conicaltaper as indicated at H corresponding to the conical taper 6 of the ribs3 and the walls ll) of said recess correspondin substantially with theconfiguration of the tapered portions of the ribs 3 and adapted toreceive the latter. Likewise, it will be understood that the walls l2conform to the configuration of the recesses formed by the flat sides 4of the ribs 3 of the bit end of the screwdriver and said walls l2 extendinto the recesses between the ribs 3 of the screwdriver when the bit end2 of the latter enters the recess 8.

In the use of the screwdriver bit illustrated in Figure 1, inconjunction with the screw illustrated in Figures 2 and 3, the bit end 2of the screwdriver is designed to fully enter. therecess 8 ofthe screwwith the bit end point I engaging the base point 9 of the recess 8, thebit end 2 frictionally and wedgingly engaging in recess 8 in the fullycooperative relation of thescrewdriver and screw.

Now referring to the form of screw'and screwdriver designed forcooperation therewith as illustrated in Figures 4, 5 and 6,the'screwdriverof Figure 4 includes a shank portion [5 and a-bit endgenerally indicated by the numeral [6. The bit or working end l6 of thescrewdriver of Figure 4 is likewise provided with alternate ribs andrecesses, there bein four of each in the embodiment illustrated, theribs being indicated by the. numeral H and the recesses beingimiicatedby the numeral l8. The ribs H are not flat sided as are theribs 3 of the form of screwdriver of Figure 1 but the recesses l8 areof'substantially concave or fluted configuration so that the extremeouter end IQ of the bit H5 is thickened and blunt and somewhat rounded,though bluntly pointed as at lac. The ribs H are conically tapered asindicated at 20 toward the blunt end 19 f the bit It, the cone anglebeingsomewhat less than the cone angle of the tapered portion of theribs 3 of the screwdriver of Figure 1,

The screw illustrated in Figures and '6 is provided with a cruciformrecess, generally indicated by the numeral 22, which substantiallyconforms to the configuration of thebit end l6 of the screwdriverillustrated in Figure 4. The walls of the recess 22 converge towardthe-outer confines 0f the blunt and somewhat rounded or concave basesocket 23 at the lower extremity of the recess 22. The walls 24 of therecess 22 correspond in configuration with the conically taperedportions 20 of the ribs 11 of the screwdriver bit illustrated in Figure4, the walls 24 of the recess 22 having the conical taper 25 corre--sponding substantially with the conical taper 20 of the ribs I! of thescrewdriver bit and the tapered portion 20 of the ribs I! being adaptedto engage the walls 24 of the recess 22. The'walls 26 of the recess 22correspond with the configuration of the recess 18 of the screwdriver'bit illustrated in Figure 4, and the rounded or convex walls 28 of therecess 22 closely engage the recesses l8 when the driver bit of Figure4- is co"- operatively associated with the screw illustrated in Figures5 and 6.

It will be noted that while the walls 24 and 26 of the recess 22converge toward the outer'com fines of the base socket 23, they do notmeet at the center of the base of the recess 22. On the other hand it isto be noted that'the t'apered'portions of the ribs 3 0f the screwdriverillustrated in Figure 1 converge to the point I, and likewise the wallsof the recess 8 of the screw illustrated in Figures 2 and 3 converge tothe base point 9. Also it may be noted that the outer extremity of thebit of Figure 4, in addition to being blunt, has ribs [1, the walls ofwhich forming the recess 18 merge with one another in the curvature ofthe fluted recesses 18 so that the walls of adjacent ribs I! are notsharply defined angularly by a sharp line of demarcationintermed'iatethe .same as is the case in connection with the fiat sided walls 4 ofthe ribs 3 of the screwdriver illustrated in Figure 1 which have theadjacent walls 4 sharply defined angularly with respect to each othermeeting in a sharp line of demarcation 5 as illustrated in Figure 1.Since the recess 8 of the screw illustrated in Figures 2 and 3 likewisehas sharply defined walls In and I2 converging at the sharp'base point 9of the recess 8, it will be apparent that the bit l6 of the screwdriverillustrated in Figure 4 is not adapted to enter the recess 8 of thescrew illustrated in Figures 2 and 3.

It willalso be apparent that the bit 2 of the screwdriver illustrated inFigure 1 will not fully enter the recess 22 of the screw illustrated inFigures 5 and 6 for proper cooperation therewith because when the bit 2is inserted in the recess 22, the pointed extremity of the bit willengage the lower rounded base socket 23 of the recess 22 before fullentrance of the ribs 3 into the recess 22 and cause the tapered edges ofthe ribs 3 to stand away from the walls 24 of the recess 22 so that theproper cooperative relation between the bit of Figure 1 and the screw ofFigure 5 cannot become established. For the foregoing reasons it will beapparent that the standard forms of screwdrivers illustrated in Figures1 and 4 (lesigned particularly for cooperation with the screwsillustrated in Figures 2 and 3 and Figures 5 and 6, respectively, arenot interchangeable for use of either screwdriver of Figures 1 and 4with the other standard form of screw.

Since a large number of screws of both of the types illustrated inFigures 2, 3, 5 and 6 is required foruse in various structures employedfor military purposes and particularly military airplanes, theGovernment has heretofore found it necessary to provide complete sets ofscrewdrivers of both of the forms illustrated in Figures 1 and 4 for usewith the various sizes of the two forms of screws illustrated in Figures2, 3, 5 and 6. Obviously, it would be very advantageous under thecircumstances to supply a single screwdriver bit which isinterchangeably adaptable for use with both types of screws, and theprovision of such a universal screwdriver bit has been the object andthe accomplishment of this invention, resulting. in a tremendous savingof critical material and other economies from the standpoint of theweight saving factor in respect to the weight of tools requiredto betransported for service of military airplanes and from the standpoint ofeconomy in actual service time in eliminating delays which wouldotherwise ensue were the particular required driver bit not immediatelyavailable.

.Now referring to Figures '7 and 8, there is illustrated in thesefigures the universal screwdriver bit of theinvention which is adaptedfor screwdriving cooperation with both of the standard formso'f screwsillustrated in Figures 2, 3, 5 and 6.

The screwdriver of Figure 7 comprises a cylindrical shank 38' having ascrew recess engaging bit 3| at one end thereof. The bit. or working end3| of the screwdriver comprises four ribs 32 extending radially from thecentral longitudinal axis of the shank 30 which is the axis of rotationof the shank when the screwdriver is bein used for driving a screw. Thisaxis is hereinafter called the driver axis. As illustrated in Figures 7and 8, the ribs 32 are equally spaced angularly around the driver axis.The bit 3| is Provided with sharply angled recesses intermediate theribs 32, said recesses being formed by the substantially flat sides 33of said ribs, the adjacent sides.33 of. each pair of adjacent ribsmeeting in a sharply defined line of juncture 34 at the angle ofsubstantially ninety degrees. The ribs 32 have a conical taper, asindicated at 35, the axis of the conical taper being common to thedriver axis, and the ribs taper inwardly toward the outer extremity ofthe bit 3|. While the tapered edges 35 of the ribs 32 converge towardthe driver axis, said tapered edges 35 do not meet, as contrasted withthe fact that the tapered edges 6 of the ribs 3 meet at the point I inthe case of the driver bit illustrated in Figure 1. The tapered edges 35of the driver bit illustrated in Figure 7 are foreshortened to provide arelatively wide and preferably flat bit end 36 constituting the outeredges of the ribs 32, the extreme outer surfaces of which preferably arein substantially a common plane perpendicular to the driver axis. Asbest illustrated in Figure 8 the bit end 36 is in the form of a clearlydefined right-angle cross and the adjacent sides of each pair ofadjacent ribs meet in substantially right-angle relationship at thesharply defined points 31 at the outermost extremity of the bit end 36.The points 31 are formed by the inward convergence of adjacent sides 33meeting in sharply defined lines of juncture 34 which extend to theoutermost extremity 36 of the bit 3|.

Upon reference to Figure 8 it will be noted that the sides of each rib32, at the extreme outer end 36 of the bit 3|,where they define thecruciform bit end 36, are substantially parallel. It will also be notedfrom Figure 8 that the adjacent sides of adjacent ribs 32, at the outerextremity of the bit 3| where they define the cruciform bit end 36, aresubstantially perpendicular to one another where they meet at thesharply defined points 31.

Preferably the angle of the conical taper 35 of the driver illustratedin Figures '7 and 8 may be intermediate the angles of the conical tapers6 and 20 of the drivers illustrated in Figures 1 and 4, but theprovision of such an intermediate angle for the conical taper 35 is notabsolutely essential to the operability of the driver illustrated inFigure 7 for the purposes of interchangeable cooperation with the screwsillustrated in Figures 2, 3, and 6. It will be apparent in any eventthat if the conical taper 35 substantially corresponds with the conicaltaper of either of the drivers illustrated in Figures 1 or 4, the driverillustrated in Figure 7 will be interchangeably cooperablesatisfactorily with the screws illustrated in Figures 2, 3, 5 and 6.

When the universal screwdriver illustrated in 1 Figure 7 is used incooperation with the screw illustrated in Figures 2 and 3 the bit end 36will, of course, not extend to the base point 9 of the recess 8 of saidscrew and yet, because of the sharply angled relationship of the meetinglines of adjacent walls of adjacent ribs at the end36 of the bit 3|, thelatter will properly enter the recess 8 and the conical edges of saidribs 32 will sufilciently engage the walls Ill of said recess 8 toestablish proper driving cooperation of the bit and screw. Likewise,since the tapered edges 35 of the ribs 32 of the driver illustrated inFigure 7 are foreshortened to terminate in the blunt end 36, the ribs 32will properly enter the recess 22 of the screw illustrated in Figures 5and 6 and sufiiciently engage the walls 24 of said recess 22 toestablish proper driving cooperation between the bit and screw.

I am aware of the United States patents of West, 2,216,381; Thompson,1,908,081; Werne, 2,235,781; Frearson, 145,411 and 308,246; andPhillips, 2,046,837; 2,046,838; and 2,046,840; and I make no claim tothe subject matter of these patents.

What I claim as new and desired to secure by Letters Patent is:

A screw driver of the class described comprising a bit, the eifectivescrew engaging portion of said bit comprising a plurality of ribsextending radially from the driver axis and terminating in a flattransverse end edge, said ribs having fiat sides, the sides of each ribconverging toward said end edge, the adjacent sides of the adjacent ribsmeeting angularly in sharply defined lines of juncture extending to theend edges of said ribs, the side edges of said ribs having a conicaltaper, the tapered side edges of said ribs converging toward the endedges of said ribs.

JOSEPH H. BISHOP.

